The most basic, common culprit and easiest to fix, is that you're not aerating enough

👇🏾yep! That’s the most common suspect. But you can’t escape if you’re steaming heavy cream unfortunately lol

Make sure to aerate the milk for atleast 3 seconds. I recommend putting the steaming wand into the milk turning the wand on and then lowering the pitcher till the wand hits the top of the milk for 3 seconds or more.